DUBAI, Oct 16 (Reuters) - The performance of banking shares weighed on Saudi Arabia's market index on Sunday after the largest listed bank reported profits below analysts' expectations, while indexes for other markets in the region also fell.

Riyadh's index fell 1.1 percent as National Commercial Bank (NCB) tumbled 5.6 percent after reporting a third-quarter net profit of 1.96 billion riyals ($523 million), down 1.6 percent from the same period of 2015. Three analysts had on average forecast a quarterly profit of 2.31 billion riyals.

NCB, like most other Saudi banks that have already reported quarterly results, cited higher costs, including a rise in impairments on financings and investments. The bank is a key lender to Saudi Arabia's troubled construction sector.

Just over half of the country's listed banks have now reported third-quarter results, with earnings generally flat or lower and the sector index was down 1.6 percent on Sunday.

Weak earnings at some mid-sized companies in other sectors also hit share prices, with medical insurer BUPA Arabia retreating 4.7 percent after posting an 8.9 percent drop in its third-quarter net income.

In Muscat National Bank of Oman lost 2.5 percent after it posted a 15.2 percent fall in its third-quarter net profit, missing analysts' forecasts. The general market index eased 0.2 percent.

Dubai's market index closed down 1 percent at 3,302 points, its lowest finish in 16 weeks. With no major companies posting results shares in small and mid-sized companies were the main movers, including builder Drake & Scull which retreated by 3.7 percent.

But telecoms firm Orange Egypt rose by its 10 percent daily limit after the company signed a 4G mobile broadband licensing deal with the government, paying $484 million and obtained 10 megahertz of radio frequency spectrum instead of the 7.5 initially on offer.

The head of Egypt's telecommunications regulator said Orange had also acquired a licence to offer fixed-line services for a further $11 million.